Rejuvenate Bio’s treatment is a gene therapy that dials up expression of the genes sTGFbetaR2 and FGF21 to reduce levels of the cytokine TGF-beta1 and boost levels of the hormone FGF21, respectively. Both genes are associated with longevity.

“What we have seen from using a combination of two genes is the ability to affect multiple age-related diseases at once,” Oliver said.

Rejuvenate Bio published data in November 2019 showing that targeting these two genes in mice reduced kidney atrophy and reversed weight gain and Type 2 diabetes. The company had given extra copies of those genes, alone and in combination with each other and another gene called alpha-Klotho to see if they could boost the mice’s health and life spans. It found out that more isn’t necessarily better, as mice that were given all three genes together fared worse than the other animals did.